Re: is there a spin_trylock_irqsave?

[Robert Love <rml@tech9.net>]

On Tue, 2002-02-26 at 21:14, Gigi Sebastian Alapatt wrote:
> 
> Is there a spin_trylock_irqsave?
> 
> Basicially
> 
> spin_once_trylock_irqsave?

No, although there is a spin_trylock_bh for whatever reason.

Implementing this would not be hard, you just need to disable irqs
_before_ spin_trylock to avoid a race.  Something like:

	int dog;
	unsigned long flags;

	local_irq_save(flags);
	dog = spin_trylock(lock);
	if (!dog)
		local_irq_restore(flags);

Oh, I'll just attach a patch.  Enjoy,

	Robert Love

diff -urN linus/include/linux/spinlock.h linux/include/linux/spinlock.h
--- linus/include/linux/spinlock.h	Tue Feb 26 20:17:12 2002
+++ linux/include/linux/spinlock.h	Tue Feb 26 21:22:22 2002
@@ -38,6 +38,12 @@
 						__r = spin_trylock(lock);      \
 						if (!__r) local_bh_enable();   \
 						__r; })
+#define spin_trylock_irqsave(lock, flags)	({ int __r;		       \
+						local_irq_save(flags);         \
+						__r = spin_trylock(lock);      \
+						if (!__r)                      \
+						local_irq_restore(flags);      \
+						__r; })
 
 /* Must define these before including other files, inline functions need them */